2015年调水调沙期间黄河悬浮颗粒Pb及其稳定同位素组成变化

通过对2015年黄河调水调沙期间利津水文站悬浮泥沙以及小浪底水库表层沉积物的分析，研究了调水调沙期间黄河入海泥沙中Pb元素的含量及同位素组成的变化特征，探讨了其物质来源及对调水调沙进程的响应.结果表明，调水调沙期间黄河入海泥沙Pb元素含量为18.09~28.35μg/g，平均为21.64μg/g，稳定同位素²⁰⁷Pb/²⁰⁶Pb为0.8367~0.8481，²⁰⁸Pb/²⁰⁶Pb为2.0839~2.0997，与黄土等物质较为接近.Pb含量及稳定同位素组成在调水调沙前、后期均较高，而在调水调沙中间主要时段则较低.利津站悬浮泥沙及小浪底水库沉积物中Pb同位素组成均符合黄河源Pb演化规律，但小浪底水库沉积物Pb元素含量较高，部分站位受到了人类活动的影响.调水调沙进程对该期间黄河入海泥沙Pb的变化及来源有着显著影响，在调水调沙前期和后期，水沙通量小，洪水对下游河床冲刷作用弱，Pb受到中上游沉积物来源影响，导致含量和同位素组成较高.在调水调沙中间的主要时段，利津悬浮泥沙与小浪底水库沉积物显著不同，Pb主要来自洪水对下游河床的冲刷，以自然来源为主，未受到人类活动影响.

Variations of Pb and its stable isotopic composition of suspended particles in the Yellow River during water-sediment regulation scheme period in 2015

Field observations and sediment samples collection were conducted at Lijin Hydrological Station during the Water-Sediment Regulation Scheme (WSRS) period from June 29 to July 20 in 2015 and Xiaolangdi Reservoir. The temporal variations, sources and influence by WSRS of the particulate trace metal lead (Pb) concentrations and its stable isotopic composition in the Yellow River were studied. The results showed that the contents of Pb in the suspended sediments from the Yellow River were ranged from 18.09 to 28.35μg/g, with average of 21.64μg/g, while the value of the stable isotope ²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb were ranged 0.8367~0.8481, 2.0839~2.0997, respectively. Both the concentrations of Pb and its stable isotope composition were higher in the early and final stages of WSRS, but lower in the middle of this period. Pb in the studied sediments was mainly natural sources, but the content of Pb in sediments of Xiaolangdi Reservoir were significantly higher, which affected by the pollution of human activities in the middle and upper reaches of the Yellow River basin. The process of WSRS has a significant impact on the variations and source of Pb from the Yellow River into the sea. In the early and final stages of WSRS, with the lower water and sediment flux, the flooding effect on the downstream riverbed was weak, so the Pb content and isotopic composition were higher, which were mainly come from the middle and upper reaches and affected by human activities. In the main period of WSRS, the suspended sediment from Yellow River to the sea was dominated by the source of the flooding to downstream riverbed, so Pb in sediments was dominated by natural sources and was not affected by human activities.